On 5 and 6 June earthlings gathered to watch Venus cross the face of the sun. We won't have that opportunity again until 2117, but on 10 November 2084 something even more wonderful will be on offer. The Earth will transit across the sun – for observers on Mars, that is. This time the valiant speck rowing across the solar disc will be us. Will anyone be there on Mars to see it?

Fifty years ago, the answer would have been a confident yes; some even hoped we'd get there in time to view the last Earth transit, in 1984. Then the possibility dwindled as Nasa turned away from manned space travel towards robotic landers such as Curiosity.

Now, the answer seems to be turning to yes again. Nasa plans to send humans to Mars in the 2030s, and sees Curiosity as preparing the way for this rather than undercutting it. Meanwhile, a private company, Mars One, has been founded by the Dutch entrepreneurs Bas Lansdorp and Arno Wielders to try to beat Nasa by sending four people to Mars in 2023. They will not just plant a footprint; they will settle, and four more people will join them every two years until the colony is self-sustaining. They will be emigrants, not explorers: initially, at least, there will be no return trips, as it's much easier to get people to Mars than to get them back.

As if this were not astounding enough, Mars One will raise the $6bn needed by doubling as a reality TV show, with private investors. Volunteers will undergo 10 years of training under the public eye, then viewers will vote on which four go first. We'll see them on their seven-month journey, then watch and talk to them as they land, assemble their homes, set out solar panels, melt Martian ice and grow food. It will be a shared ride; the company have already recruited a veteran of the original Dutch Big Brother to organise it.

Lansdorp and Wielders are gambling on human curiosity – on human nature. You could even say that they are getting humanity to Mars using human nature itself as fuel. If they succeed, Nasa will land to find a Big Brother house already there. How will Nasa respond? Will it go sooner, be bolder, plan a colony instead of a visit? Almost anything could happen.

The nightmare possibilities of Mars One project are obvious. If the media novelty wears off, the settlers might be abandoned a few years after landing. Technical failures, with loss of life, could scupper future support for Mars travel. And Mars may become the property of a private company – a terrifying thought. But perhaps there is hope in the heart of these terrors.

In the 1990s, the entrepreneur Craig Venter similarly threatened to beat the public Human Genome Project to the sequencing of the human genome. Had he won outright, humanity's genetic essence would now be owned by private investors charging for its use. Instead, the project raced heroically faster, and they and Venter announced a joint result in 2000, with access free to all. Venter later said this was all he wanted: to make things happen.

Could we see something like this with Mars? Also, what about Earth? The big puzzle facing Earth-dwellers at the moment is how to motivate ourselves to do things clearly worth doing, but lacking immediate pay-offs. Our feeble response to the environmental crisis is a glaring case. To outwit ourselves, we need to harness our own psychology in new ways, and trick ourselves into doing good.

Could there be a genius of human motivation out there, ready to dream up some psychologically astute Earth One project? It might rest on some strange or frightening ploy at first, but if it rescues life on Earth, we'll have it.

And if it works, second-generation human Martians might not only watch the transit of Earth in 2084, but marvel at how that little round silhouette bears such foolish but inventive beings, and how they have achieved such wonders despite (and because of) themselves.